Provides an effect similar to shooting black-and-white photographs with a color filter. Y (yellow), O (orange) and R (red) are effective to emphasize the contrast, with contrast strengthening in the order Y to O to R. This is useful when you want to decrease the brightness of the sky to make the scene look deeper and denser. G (green) provides a similar effect to shooting black-and-white photographs with a green filter, making some areas of an image appear deeper and denser. This can make the skin tone or lips look subdued, which is effective for portrait photography.